In accordance with a first aspect of this invention, there is provided a ballistic projectile including
a body portion defining an internal cavity and having a surround around the cavity, the surround having a peripheral slide surface;
a cover portion having a peripheral slide surface complemental to said slide surface of the surround to render the body portion and the cover portion slidably closable onto each other to close the cavity;
complementally arranged peripheral seats in the respective slide surfaces, and a generally peripheral band seated in said seats such that the band bridges an interface between, and inter-secures, the body portion and cover portion.
The projectile may be round.
At least one of the surround, the cover portion and the peripheral band may be resilient to allow assembly. In practice, the peripheral band may be resilient. Thus, in a preferred embodiment, the slide surfaces may be round, and the band may be in the form of a resilient ring.
The resilient ring may be a split ring to allow a cross dimension thereof to be reduced/increased by compression/expansion, one of the seats being of sufficient capacity to accommodate the ring fully to allow the ring to be strained fully into said one seat to cause the ring to be flush with or shy of the corresponding slide surface.
Advantageously the seats and the band may be arranged to be concealed when assembled to render the projectile unopenable from externally and thus tamper proof.
Preferably, the band or the resilient ring may be a shear ring designed to fail at a predetermined shear force. Then, the ballistic projectile may include a pressure generator for generating internal pressure to a corresponding, predetermined pressure to shear the ring and to cause the cover portion to part from the body portion to expose the cavity. The ballistic projectile may be a base ejection projectile, the projectile including a pressure generator in the form of a propellant charge for generating internal pressure to a predetermined value to shear the ring and to cause the cover portion to part from the body portion to expose the cavity.
In accordance with a second aspect of the invention, there is provided a method of closing a ballistic projectile in accordance with the first aspect, the method including
seating the band in one of the seats;
straining the band to be fully received within said one seat;
retaining the band fully in said one seat and closing the cover portion onto the body portion to register the seats;
causing the band to relax to move only partially out of said one of the seats and to move partially into the opposing other of the seats interlockingly to inter-secure the body portion and the cover portion.
The peripheral slide surface of the cover portion may fit inside the peripheral slide surface of the surround, the method including compressing the ring into the seat by means of a compression sleeve covering only a portion of the ring to allow the uncovered portion to be slid within the surround to hold the ring to allow the compression sleeve to be removed to allow the ring to be slid into register with the opposing seat. Once registered, the ring expands under its resilience to enter the opposing seat to bridge the interface.
In accordance with a third aspect of the invention, there is provided a method of opening a ballistic projectile in accordance with the first aspect, the method including generating pressure within the enclosed cavity to a sufficient degree to shear the band to cause the cover portion to part from the body portion under the internal pressure. Thus, generating internal pressure may be by initiating a propellant charge exposed to the cavity.
The method of opening the ballistic projectile may include the prior step of providing sealing between the respective slide surfaces to facilitate internal pressure generation.